Oracle LAST_DAY function in SQL Server

Today I was working in SQL Server 2008. I need to use a function similar to Oracle's LAST_DAY in my scripts, but I cannot find an equivalent function, so I decided to perform a new one.

This is the script to build the function in SQL Server:

CREATE FUNCTION [dbo].[LAST_DAY] ( @pInputDate    DATETIME )

RETURNS DATETIME

BEGIN

    DECLARE @vOutputDate        DATETIME

    SET @vOutputDate = CAST(YEAR(@pInputDate) AS VARCHAR(4)) + '/' +

                       CAST(MONTH(@pInputDate) AS VARCHAR(2)) + '/01'

    SET @vOutputDate = DATEADD(DD, -1, DATEADD(M, 1, @vOutputDate))

    RETURN @vOutputDate

END

These are the test scripts in SQL Server and Oracle:

• SELECT dbo.LAST_DAY(getdate())

• SELECT LAST_DAY(TRUNC(SYSDATE)) FROM dual

The result row in both scripts was: 2012-10-31 00:00:00.000